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The Effect of the Wall Contact and Post-Growth C001-Down on Defects in CdTe Crystals Grown by Contactless PVTIn crystal growth, the quality of the final material may depend, among other factors, on its interaction with the walls of the ampoule during and after the growth, and on the rate of the crystal cool-down at the end of ate the process. To investigate the above phenomena, a series of CdTe crystal growth processes was carried out, The crystals were grown by physical vapor transport without contact with the side walls of the silica glass ampoules, applying the Low Supersaturation Nucleation technique. The source temperature was 930 C, the undercooling was a few degrees. The crystals, having the diameter of 25 mm, grew at the rate of a few mm per day. The post-growth cool-down to the room temperature was conducted at different rates, and lasted from a few minutes to four days. The crystals were characterized using chemical etching low temperature luminescence, and Synchrotron White Beam X-ray Topography techniques. The dislocation (etch pit) density was measured and its distribution was analyzed by comparison with Poisson curves and with the Normalized Radial Distribution Correlation Function. It was found that the contact of the crystal with silica leads to a strain field and high (in the 105 sq cm range) dislocation (etch pit) density. Similar defect concentrations were found in crystals subjected to fast post-growth cool-down. Typical EPD values for lower cool-down rates and in regions not affected by wall interactions are in the lower 10(exp 4) sq cm range. In some areas the actual dislocation density was about 10(exp 3) sq cm or even less. No apparent effect of the cool-down rate on polygonization was observed. A fine structure could be discerned in low-temperature PL spectra of crystals with low dislocation density.
Document ID
20010048755
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Palosz, W.
(Universities Space Research Association Huntsville, AL United States)
Grasza, K.
(Polish Academy of Sciences Warsaw, Poland)
Dudley, M.
(State Univ. of New York Stony Brook, NY United States)
Raghothamachar, B.
(State Univ. of New York Stony Brook, NY United States)
Cai, L.
(State Univ. of New York Stony Brook, NY United States)
Durose, K.
(Durham Univ. United Kingdom)
Halliday, D.
(Durham Univ. United Kingdom)
Boyall, N. M.
(Durham Univ. United Kingdom)
Rose, M. Franklin
Date Acquired
August 20, 2013
Publication Date
January 1, 2001
Subject Category
Solid-State Physics
Meeting Information
Meeting: ICCG13
Location: Kyoto
Country: Japan
Start Date: July 30, 2001
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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